This invention relates to a security attachment for an electrical plug which is effective to prevent unauthorized use but which readily permits authorized use.
In the United States and Canada, household electrical appliances are typically provided with plugs which are intended to be connected into electrical wall receptacles. The plug is usually a two prong type comprising a non-conductive body containing two electrical terminals. An insulated wire containing two separate conductors leads from the plug to the electrical appliance. One conductor of the wire connects to one prong within the plug body while the other wire connects to the other prong also within the plug body. The wall receptacle comprises two sockets containing terminals into which the prongs of the plug are plugged. The receptacle socket terminals are "live", meaning that a voltage exists across them which can be used to power the electrical appliance containing the plug. Hence, when the plug is plugged into the receptacle, circuit continuity is established such that current can flow to the appliance via one conductor and return via the other conductor. Typically the power supplied to household wall receptacles in the United States is 115 volts, 60 hertz AC, and hence the current flow is of alternating polarity at the AC frequency.
For any of a number of various reasons it may be desirable to control the usage of an electrical appliance so as to prevent unauthorized use yet permit authorized use. For example, with the advent of home video games, children can become addicted to playing them, and hence parental control of the use of such video games becomes very important. Unfortunately, it may not always be convenient for parental supervision to be exercised, such as for example when both parents are working and the children come home from school before the parents can come from work.
A novelty search conducted in connection with this invention has revealed that the prior art contains a myriad of electrical security devices for preventing unauthorized use and permitting authorize use. A vast majority of prior devices comprise lockouts in which either the plug or the receptacle is physically locked out by means of a locking device which prevents mating engagement of a plug and receptacle. U.S. Pat. No. 3,416,123 is an example of a lockout plug device applied to an electrical plug.
Many of these prior lockout devices are key operated and contain a lock mechanism. The authorized user controls the key, and hence it is possible for that person to apply the lock to the plug so that use of the appliance or device containing the plug is prevented until such time as he or she returns with the key to unlock the lock. In order to provide adequate security, such locks must often be of sufficient size and strength so that they may be relatively expensive.
The present invention is directed to a security attachment for an electrical plug which is effective to control use of a device containing the plug yet which is considerably less complicated than the locking devices of the prior art. It is deemed to be highly effective in controlling use of electrical devices such as video games by children. It does not require a locking mechanism in the sense of prior locking device utilizing padlocks, combination locks, etc. Rather, it employs two electrical adapters arranged in a new and unique manner. One adapter, in the preferred embodiment, is connected to the plug in a manner effective to prevent the two from being unplugged and to discourage children from attempting to defeat the connection. It also has prongs which are impossible to connect into the receptacle. Authorized use is permitted by plugging the second adapter into the first. When the two adapters are so plugged together, the second adapter comprises prongs which can be plugged into the wall receptacle. In this way, the two adapters, when plugged together and between the receptacle and the plug, provide electric circuit continuity from the receptacle to the plug such that electrical power from the receptacle is delivered to the electrical device or appliance containing the plug.
One advantage of the preferred embodiment of the invention as disclosed herein is that it can be sold in kit form for use with existing appliances. In other words, the owner of an electrical appliance can buy the kit, install it on the appliance plug, and control use of the appliance. First, the owner plugs the plug of the appliance into the first adapter; he or she then installs the connector which connects the first adapter to the plug to prevent the two from being unplugged. The owner then controls the use of the second adapter to thereby exercise control over use of the appliance.
The search referred to above also developed U.S. Pat. Nos. 2,761,109; 3,161,450; and 3,363,214. While between a plug and a receptacle, it is neither involved with nor suited for unauthorized use prevention. In a corresponding allowed U.S. Pat. application Ser. No. 466,406 filed Feb. 15, 1983, now U.S. Pat. No. 4,494,809, issued Jan. 22, 1985 the only references cited were U.S. Pat. Nos. 3,363,214 and 3,811,104 and the original claims were allowed over those references.
The foregoing features, advantages and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention according to the best mode contemplated at the present time in carrying out the invention.